I am new to this forum so maybe this has been covered. I had a Gravely Z44 for 13 years and never noticed this. I bought a new ZT HD 48. It now has 20 hours on it. The transmission fluid in the reservoir was almost clear when new, now after only 20 hours it is dark brown. This seems quick to me. I talked to the dealer on the phone and he said it is normal. Has anyone else seen this in their new mower? This dealer has misled me in the past. Thanks for your help.